Bad Weather, Errors A Deadly Mix

Despite the dark clouds and lightning, Delta Flight 191 Capt. Edward Connors seemed relaxed as he requested permission to land his Lockheed L-1011 at Dallas-Fort Worth International Airport.

"Tower, Delta 191 heavy, out here in the rain. Feels good," Connors radioed to the control tower at 6:03 p.m. on that hot summer day, Aug. 2, 1985.

Two minutes later, the three-engine jumbo was caught in the grip of a powerful downdraft known as wind shear. Connors implored his co-pilot, who was at the controls, to give the plane as much power as possible and attempt to climb out of trouble.

"Push it up," he said, referring to the throttles. "Push it way up. That's it."

But it was too late. The plane, which had taken off from Fort Lauderdale three hours earlier with 152 passengers and 11 crew members, smashed down 1 miles short of the runway. It hit a car on a highway, bounced back up into the air, slammed into a water tank, broke apart and caught fire. In all, 137 died.

Although pilot error is to blame in about 37 percent of U.S. airline accidents, weather is the major factor in 24 percent, according to the National Transportation Safety Board.

From 1989 to 1997, there were 60 weather-related airline accidents, according to a Federal Aviation Administration weather study.

Of those, 79.7 percent were the result of turbulence and 6.3 percent the result of heavy rain. Thunderstorms, high winds and icing each accounted for 3.1 percent of the accidents. Wind shear, poor visibility and hot weather -- which can erode a plane's performance -- each accounted for 1.6 percent.

Wind shear, one of the deadliest conditions, is responsible for at least three airline crashes and more than 230 fatalities since 1980.

Delta Flight 191 was an example of how bad weather mixed with human error resulted in disaster, aviation experts say. The NTSB blamed the flight crew for attempting to land even though crew members knew a thunderstorm lurked ahead.

Largely as a result of Delta Flight 191, the FAA undertook a $375 million program to install Terminal Doppler Weather Radar at 45 commercial airports that have frequent thunderstorms. The radar, which can detect wind shear's conflicting up and down currents, is now operational at 39 airports, including Miami and Palm Beach International.

Although up and running, the system for Fort Lauderdale-Hollywood International Airport is in a testing phase and will not be officially commissioned until later this year. Doppler radar also is to be operational at airports in New York, Salt Lake City, Las Vegas, Chicago's Midway and San Juan by the end of the year.

At a recent U.S. House aviation subcommittee hearing, Jim Hall, NTSB chairman, said Doppler should be installed at many more small and medium-sized airports.

He said that had the sophisticated radar been in place, it might have prevented the American Airlines crash in Little Rock, Ark., in June. In that accident, a McDonnell-Douglas MD-82 attempted to land in a thunderstorm, got pushed off the runway by winds up to 87 mph and careened into a light structure, killing 11 of the 145 aboard.

Steven Brown, the FAA's associate administrator for air traffic, said the agency has been working with the National Weather Service to provide air traffic controllers and pilots with the most up-to-date weather conditions even at airports where Doppler is not available.

But even with the best equipment, he said, technology might not stop weather-related aviation accidents.

"Technology is only one piece of the puzzle. The other equally important pieces are pilot training and pilot judgment," he said.

Airline pilots were not aware of how dangerous a thunderstorm can be for a jetliner until the crash of Northwest Airlines Flight 705 almost four decades ago.

The Boeing 720, bound for Chicago, took off from Miami International Airport into a sky full of thunderstorms on Feb. 12, 1963. It was still the dawn of the jet era and the Northwest pilots had perhaps too much confidence in the structural strength and power of their four-engine aircraft, aviation authorities said.

Fifteen minutes into the flight, the jet was jarred by a thunderstorm's massive updrafts and downdrafts, broke apart in flight and plunged into the Everglades, killing all 43 on board. It was the first time a U.S. jetliner had disintegrated in midair as a result of severe weather.

That tragedy taught pilots to circumnavigate thunderstorms as much as possible. If caught, pilots now know not to fight vertical air currents by pitching the nose up and down, but rather to maintain a level flight attitude.

Brown said pilots need to be cautious of any number of weather conditions, not just thunderstorms.

"The pilot must make tactical decisions based on information such as reports on the cloud ceilings, visibility, thunderstorms, turbulence, icing, wind shear, winds aloft, and even volcanic ash clouds," Brown said.

"Armed with this information, pilots can plan around bad weather and commercial operators can plan routes that are both safe and economical, given the tremendous economic ramifications that weather can have on airlines."